Abstract

Surface enhanced absorption spectroscopy in Mid-Infrared (Mid-IR) spectral range is of great interest as it enables direct access to vibrational information of most organic molecules and biosamples, including protein monolayers, by providing orders of magnitude signal enhancement compared to the traditional spectroscopy techniques[1]. For applications associated with extremely low signal levels, such as biosamples with ultralow analyte concentrations, high signal-to-noise ratio (SNR) is required for reliable spectroscopic analysis within minimum detection time. Under such circumstances, to increase the SEIRA signal levels, it is important to (i) maximize the field overlap with the target biosample and (ii) preserve the maximum number of photons interacting with the sample. In this work, we introduce a polarization insensitive Mid-IR nanoring antenna fabricated on a dielectric nanopedestal to provide maximum field overlap with the target biomolecules[2]. The antenna system, by supporting highly accessible electromagnetic fields, strongly enhances the absorption signals. Our suspended ring antenna design on nanopedestal is highly promising for ultrasensitive Mid-IR vibrational spectroscopy specifically for applications requiring high SNR.

© 2015 IEEE